Question

how to write a 2-3 page paper description of the physiology function of the brain

Answer 1

BRAIN:

1. Brain is a very sof tissue and is surrounded by a bony case called CRANIUM, which is made up of skull bones. CRANIUM protects the brain from injuries.
2. Brain is divided into three parts-forebrain, mid brain and hind brain. The hind brain continues as spinal cord.

The following is the digramatic representation of BRAIN.

  

entricles FOREBRAIN Cerebrum rpus callosum Thalamus Hypothalamu Pituitary gland Cerebellum Pons HINDBRAIN Medulla Brain stem

FOREBRAIN:

1. Forebrain is the largest part of the brain. This is also called as CEREBRUM.
2. A deep groove in the middle of cerebrum divides it into two equal halves. Each half is called as CEREBRAL HEMISPHERE(Right and Left).
3. Right and Left cerebral hemispheres are connected to each other by a bundle of axons.
4. The outer portion of the cerebral hemispheres is grey in colour and is called CEREBRAL CORTEX.
5. There are several ridges(elevations) called GYRI(Gyrus in sinular) and grooves called SULCI(Sulcus in singular) on the surface of brain.
6. They increase the surface area of cortex so that it can accommodate more number of neurons.
7. Three very deep grooves present across each cerebral hemisphere divides into four lobes - FRONTAL, PARENTAL, TEMPORAL and OCCIPITAL LOBES.
8. Cerebrum is the highest center for controlling several functions in the body.
9. Most interesting aspect of cerebrum is that right hemisphere controls the functions of the left side of the body and the left hemisphere controls the functions of the right side of the body.
10. In the cerebral cortex there are centers to recieve and analyse various informations.
11. Ex: Visual(sight), auditary center(hearing), olfacory(smell), etc.
12. Cerebrum is the seat of intelligence, thinking and judgement.
13. Parts of the brain below the cerebrum are together known as diecephalon.
14. This portion of the brain has centers that control emotions such as anger, pain and pleasure.
15. This portion also connects the forebrain with mid brain.
16. Hypothalamus present in this section of brain secretes harmones.
17. Pitutary which is endocrine gland is attatched to a hypthalamus by a stalk.
18. Hypothalamus also has centres for regulating body temperature, hunger thirst and emotions. It also secretes harmones.

MID BRAIN:

1. The mid brain consists of groups of nerve cells and a large number of myelinated axons of the nerve cells present in other regions of the brain.
2. Some of the nervecells in this region control the body muscles and their movements.

HIND BRAIN:

1. Hind brain consists of two parts - CERBELLUM and BRAIN STEM.
2. Cerebellum lies behind the cerebrum and has grey matter on the surface of the white matter in the deeper layers.
3. Cerebellum controls all the voluntary movements of the body. It is also responsible for the maintenance of equlibrium and posture of the body.
4. Brain stem has two parts - PONS VAROLI and MEDULLA OBLONGATA.
5. The later continues as Spinal cord and medulla oblongata the white matter is on the surface and the grey matter is the deeper layers.
6. Medulla oblongata has centres to control several vital functions of the body such as respiration, heart beat, blood pressure, secretion by salivary glands, etc.
7. Medulla oblongata continues as Spinal cord. All the nerve fibers from brain pass through Medulla Oblongata into spinal cord.

Other important parts of the brain

CEREBROSPINAL FLUID (CSF):

1. The cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds, cushions and protects the brain and spinal cord.
2. The CSF also carries nutrients from the blood to, and removes waste products from, the brain. It circulates through chambers called ventricles and over the surface of the brain and spinal cord.
3. The brain controls the level of CSF in the body.

MENINGES:

The brain and spinal cord are covered and protected by 3 thin layers of tissue (membranes) called the meninges:

• dura mater – thickest outer layer
• arachnoid layer – middle, thin membrane
• pia mater – inner, thin membrane

CSF flows in the space between the arachnoid layer and the pia mater. This space is called the subarachnoid space.

1. The tentorium is a flap made of a fold in the meninges. It separates the cerebrum from the cerebellum.
2. The supratentorial area of the brain is the area above the tentorium. It contains the cerebrum, the first and second (lateral) ventricles, the third ventricle, and glands and structures in the centre of the brain.
3. The infratentorial area is located at the back of the brain below the tentorium. It contains the cerebellum and brain stem. This area is also called the posterior fossa.

CORPUS COLLASUM:

The corpus callosum is a bundle of nerve fibres between the 2 cerebral hemispheres. It connects and allows communication between both hemispheres.

THALAMUS:

The thalamus is a structure in the middle of the brain that has 2 lobes or sections. It acts as a relay station for almost all information that comes and goes between the brain and the rest of the nervous system in the body.

HYPOTHALAMUS:

1. The hypothalamus is a small structure in the middle of the brain below the thalamus. It plays a part in controlling body temperature, hormone.
2. A substance that regulates specific body functions, such as metabolism, growth and reproduction. secretion, blood pressure, emotions, appetite, and sleep patterns.

PITUITARY GLAND:

1. The pituitary gland is a small, pea-sized organ in the centre of the brain. It is attached to the hypothalamus and makes a number of different hormones that affect other glands of the body’s endocrine system.
2. The group of glands and cells in the body that make and release hormones (which control many functions such as growth, reproduction, sleep, hunger and metabolism) into the blood.. It receives messages from the hypothalamus and releases hormones that control the thyroid and adrenal gland, as well as growth and physical and sexual development.

VENTRICLES:

The ventricles are fluid-filled spaces (cavities) within the brain. There are 4 ventricles:

1. The first and second ventricles are in the cerebral hemispheres. They are called lateral ventricles.
2. The third ventricle is in the centre of the brain, surrounded by the thalamus and hypothalamus.
3. The fourth ventricle is at the back of the brain between the brain stem and the cerebellum.
4. The ventricles are connected to each other by a series of tubes. The fluid in the ventricles is cerebrospinal fluid (CSF). The CSF flows through the ventricles, around the brain in the space between the layers of the meninges (subarachnoid space) and down the spinal cord.

PINEAL GLAND:

The pineal gland is a very small gland in the third ventricle of the brain. It produces the hormone melatonin, which influences sleeping and waking patterns and sexual development.

CHOROID PLEXUS:

The choroid plexus is a small organ in the ventricles that makes CSF.

CRANIAL NERVES:

There are 12 pairs of cranial nerves that perform specific functions in the head and neck area. The first pair starts in the cerebrum, while the other 11 pairs start in the brain stem. Cranial nerves are indicated by number (Roman numeral) or name.

Cranial nerves and their functions

1. olfactory - smell
2. optic - vision and light detection by the pupil
3. oculomotor - eye movement upward, downward or inward narrowing and widening of the pupil lifting of the eyelid
4. trochlear - eye movement downward and inward
5. trigeminal - facial sensation chewing
6. abducens - outward eye movement
7. facial - facial expression closing of the eyelid taste in the front part of the tongue
8. acoustic - hearing balance
9. glossopharyngeal - swallowing gag reflex speech
10. vagus - swallowing gag reflex speech (vocal cords) control of muscles in internal organs
11. accessory - neck turning shoulder shrugging
12. hypoglossal - tongue movement

BLOOD-BRAIN BARRIER:

1. The blood-brain barrier is a specialized system of blood vessels and enzymes.
2. A protein that speeds up certain chemical reactions in the body. that protect the brain from chemicals or toxins produced by bacteria. It helps maintain a constant environment for the brain.
3. The blood-brain barrier is made up of very small blood vessels (capillaries) that are lined with thin, flat endothelial cells. In other parts of the body, endothelial cells have small spaces between them that allow substances to move in and out of the capillary so they can reach other cells and tissues. In the brain, the endothelial cells are packed tightly together so substances cannot pass out of the bloodstream into the brain. The enzymes also restrict the types of substances that can be carried from the bloodstream into the brain.
4. Some substances can pass through the blood-brain barrier, such as very small molecules and molecules that can be dissolved in fat (are lipid soluble).

Types of cells in the brain

The brain is made up of neurons and glial cells:

NEURONS:

1. These cells carry the signals that make the nervous system work.
2. They cannot be replaced or repaired if they are damaged.
3. glial cells (neuroglial cells)
4. These cells support, feed and protect the neurons.

The different types of glial cells are:

• astrocytes
• oligodendrocytes
• ependymal cells
• microglial cells